To study surface changes in transformed cells and the molecular mechanisms responsible for antigenic changes and/or the transformation to malignancy, either spontaneously or as induced by SV40 virus. To develop methods to isolate and purify cell surface membranes, and antigenic components such as SV40 virus specific surface antigens and tumor specific transplantation antigens; and to study their interrelationships. BIBLIOGRAPHIC REFERENCES: Chang, C., Pancake, S.J., Luborsky, S.W. Mora, P.T.: Detergentsolubilization and partial purification of tumor specific surface and transplantation antigens from SV40 virus transformed mouse cells. Int. J. Cancer 19: 258-266, 1977. Coll, J.M., Luborsky, S.W. and Mora, P.T.: Metabolically labelled cell membrane proteins in spontaneously and in SV40 virus transformed mouse fibroblasts. Biochem., 1977, in press.